We’ve come a long way since the first systems that pulled horse-drawn carts to a standstill were used. Back then, a wooden block was pressed against the circumference of the wheel, generating friction and bringing the carriage to a halt. This method was even used on some of the first cars, with a block pressing against the outside of the rubber tyre.
Slowly but surely the brake blocks (now known as shoes) were moved closer to the axle and housed inside a metal liner (drum), creating the 'drum' brake. Drum brakes are still fitted on the rear axle of many new cars, as the rear axle doesn’t convert as much kinetic energy into heat as the front. However, the front axle needs a setup that isn’t prone to overheating and losing efficiency. This is where disc brakes come in. They feature a disc that rotates with the axle, plus a caliper in a fixed position containing pads that can pinch the rotating disc.
The disk brake was first patented in 1902 by Lanchester Cars, however it used copper brake pads which wore too quickly, and wasn't very practical. Various versions and adaptations were used until a disk brake that resembles what we see now - courtesy of Jaguar with their C-type race car - was introduced in the 50's.
Jaguar first showcased the advantages of their disc brakes at Le Mans in the 1953. The reduction in fade due to the open-disc design meant that the cars could brake later and harder than drum-equipped rivals. It wasn't until 1955 that a mass production car came with disk brakes. The 1955 Citroën DS came with in-board front disk brakes. In the years that followed, disc brakes would become the norm on the front axle of road cars.
We now have various types of disk brakes with the most common type being the conventional cast iron disk setup. Cheap to produce, and more than adequate for your average commuter, the cast iron disk brake dominates the market. But what happens to cast iron brakes when abused, say for example, when used on sports cars?
Cast iron disk brakes can suffer from 'brake fade' when used repeatedly and under high-speed conditions. This phenomena comes in various forms, and presents itself as a reduction in stopping power (mechanical fade) or a 'long' brake pedal (fluid fade).
Mechanical fade is when the temperatures get so high, that a layer of gas can build up between the disk and pad, reducing stopping power. Fluid fade is when the same high temperature finds its way to the brake fluid which can boil. This changes the properties of the fluid meaning that the brake pedal can go to the floor, reducing braking performance.